In December 2016, the National Energy Administration of China (NEA) announced that it intends to establish a Coal Coupling Power Demonstration Programme, as part of the Clean Power Plan in China’s 13th Five Year Plan (2016-2020). The programme promotes the cofiring of coal with biomass (agricultural and forestry wastes, especially straw) and sludge. The IEA Clean Coal Centre (CCC), together with the Electric Power Planning and Engineering Institute of China (EPPEI), agreed with the NEA to run a special workshop to consider how to enable the cofiring of coal with biomass in Chinese power plants. This took place on 7-8 June, at the Asia Hotel in Beijing, China. It brought together some 40 experts from Australia, Canada, Denmark, Finland, Germany, Japan, the Netherland, Singapore (France), Sweden, Thailand, and the UK, who came to China to share their expertise with about 270 Chinese stakeholders from national and provincial government departments, utilities, institutes, and universities.
The workshop was opened by Dr Andrew Minchener OBE with an introduction to the IEA CCC and the workshop. The vice president, of EPPEI Mr Sun Rui, welcomed the delegates, on behalf of the president of EPPEI. He summarised EPPEI’s current work and stressed the importance of cofiring biomass with coal in China. Mr Guo Wei, the deputy counsel from NEA, praised the Chinese strategy of cofiring biomass with coal. He suggested that different ministries would cooperate and issue relevant policies in order to promote cofiring in China.
Mr Sun Rui started the technical sessions by sharing the ‘Development prospects of cofiring biomass with coal in China’. As a large agricultural country, China has abundant biomass resources. By 2020, the coal-fired power capacity will be 1100 GWe; if 50% of it can be retrofitted to cofire biomass, at an average blending ratio of10% energy basis, the biomass power installed capacity can easily reach 55GWe. The biomass power generation benchmarking price is 0.75 yuan/kW (tax inclusive) in China; part of the price is paid by the grid according to the local coal-fired power generation benchmarking price, and the rest is paid by the National Renewable Development Fund. China has some experience of cofiring biomass, but international technologies and experience are much needed. Mr Sun suggested that the government should allow cofiring biomass with coal to share the same subsidy as 100% biomass firing and that relevant organisations should be entrusted to regulate the measurement of biomass used in cofiring projects to ensure the accuracy of biomass power generation.
China needs to avoid the mistakes made in Europe when setting up supportive policies, such as subsidy schemes. To help achieve this, the workshop included a session on incentivisation and related issues. Dr Minchener introduced the UK policies on biomass utilisation. Mr Carbo described the Netherlands SDE + scheme. Mr Nieminen described the Finnish plan on coal and biomass cofiring and a method developed by VTT Technical Research Centre of Finland to monitor/verify the proportion of biomass fired. Dr Jia Li gave a spatio-techno-economic analysis on whether China should subsidise cofiring to meet its 2020 bioenergy target. Most importantly, it showed good compatibility between major locations of agricultural residues and significant concentrations of coal fired power plants, so limiting possible residue transport costs.
International engineering experiences for retrofit of coal cofiring projects were shared by the Canadian Wood Pellet Association, DONG Energy, Energy Research Centre of the Netherlands (ECN), Engie, Gexcon, Greenbank, IFK Germany, Mitsubishi Hitachi Power Systems Europe GmbH, Sandvik Materials Technology, Sheffield University, and VTT Technical Research Centre of Finland. The subjects covered included: converting coal-fired power plant, biomass handling and preparation, monitoring and verification of the proportion of biomass fired, prevention of fires and explosions, deposition and slagging, emissions and ash characteristics, and new materials for boilers. Mr Nieminen also presented his knowledge on cofiring coal with sludge. The Chinese presenters reported their experiments on 100% biomass firing and cofiring, biomass gasification and biomass CFB gasification coupling with large scale coal-fired power plant, ash related issues, and sludge drying and pulverising for firing for power generation. There was extensive discussion between all participants.
The workshop was closed by Dr Minchener with a speech summarising the positive outcomes from the event. Cofiring in China is a win-win situation with very significant potential to fire various agricultural residues and other wastes with coal in large power plants in China both as a means to reduce carbon emissions and to counter local air pollution. The Chinese government announcement to increase the use of renewable energy sources in the electricity sector, which supports the use of biomass cofiring, and contributes to reducing CO2 emissions, is the first step. Along with the NEA plan to demonstrate cofiring technologies prior to large scale deployment, this means that some key drivers for technology deployment are now in place. Initial studies show that a suitable subsidy is needed. Regional differentials need to be considered to best focus the most promising technology deployment opportunities.
Biomass has very different properties to coal and it will be necessary to determine the characteristics of the ash. Several engineering challenges have been highlighted, including those due to using straw and sludge rather than wood pellets – the prime feedstock for cofiring in Europe. Ultimately, these issues should not present a significant barrier to cofiring with coal in China. However, these challenges will have to be fully addressed and the solutions maintained to avoid major problems occurring. Such engineering solutions will have costs.
Handling and processing agricultural biomass and sludge can improve their combustion characteristics through pelletisation and torrefaction. But such improvements also come at a cost. Torrefaction plants require significant capital costs (and large feedstock availability to compensate for the investment), but are expected to have lower operational costs than pelletisation plants.
With hindsight we should have talked more about costs while recognising they will be project specific. A stable and cheap flow of biomass is essential to sustaining a biomass cofiring project. It is therefore important to avoid repeating previous incidents in China when straw prices rose to unsustainable levels and caused damage to rural economies. On the other hand, the use of waste streams from agriculture and forestry should also create additional value and job opportunities, and contribute to rural development, while addressing a disposal challenge that already is a major component of poor air quality. There may be niche opportunities to dispose of specialist wastes and sludges that can command a significant gate fee, while also helping to build China’s circular energy economy.
Dr Minchener pointed out that the Chinese government has yet to identify a clear way forward that will ensure a clear delineation for Ministerial responsibilities and ensure a consistent incentive scheme is put in place required for investors to have confidence in this lower carbon technology option. China needs to avoid the mistakes made in Europe with the various subsidy schemes and seek to put in place a robust consistent approach while paying full attention to addressing sustainability issues. The need for a transparent means of auditing the proportion of biomass used is critical. The EU approaches may not suit the Chinese situation. However, a novel technique was identified, which needs to be trialled at large industrial scale.
The sustainability of the bioenergy should be ensured, including protection of soil and water resources, biodiversity, land allocation and tenure, and food prices, energy access, infrastructure, and training of a workforce.
There would also appear to be scope for international cooperation in R&D, particularly with biomass processing and feeding since Chinese feedstocks will be different to those used elsewhere. Research institutes around the world are working on the improvement and standardisation of biomass pellets in terms of energy density, humidity, environmental properties, durability, and the entire production process, from the raw material to storable pellets. There is also scope for a more generic understanding of the behaviour of biomass in large power station boilers and to determine simpler means to avoid performance degradation due to the ash components, which are quite different to those from coal.
Dr Minchener concluded that EPPEI and IEA CCC see this workshop as a starting point so that China can build on the international experience, thereby allowing safe short cuts in the learning experience to establish large scale demonstrations of cofiring agricultural residues and sludges with coal in large power station boilers, to be followed by robust deployment of the technology on a commercial basis.
Although a USB, containing most of the presentations and a selection of IEA CCC publications on cofiring in both Mandarin Chinese and English, together with other key information from EPPEI, was given to each delegate at the workshop, the IEA Clean Coal Centre will upload the presentations to the workshop website as well, http://cofiring7.coalconferences.org/.
The IEA Clean Coal Centre will be pleased to help facilitate interactions, working alongside our partners from EPPEI who have a key role to play in the Chinese initiatives. We will build up a full participants’ database, using information provided at registration, and make it available to all the delegates.
EPPEI and IEA CCC will look at possibilities for further workshops, once the Chinese demonstration programme gets underway and possible R&D cooperative initiatives have been established.